Hood for dryer

ABSTRACT

Hood for continuous web dryer supported on crankarms for swinging movement toward and away from web. Centering means provided to fix center of hood and cause expansion and contraction to occur from center to each end of hood.

Portouw 1 Dec. 24, 1974 11001) FOR DRYER 3,363,665 1/1968 Daane et a1 34/114 inventor: Robert C. Portmnw, Portland eg 3,541,697 11/1970 V1l1alobos 34/122 X [73] Assignee: Drew Engineering Co., Portland, FOREIGN PATENTS OR APPLICATIONS g 710,353 9/1941 Germany 1. 34/122 [22] Filed: 2, 1971 Primary ExaminerCarroll B. Dority, Jr. [21] AppL NO: 120,258 Attorney, Agent, or Firm-Klarquist, Sparkman,

Campbell, Leigh, Hall & Whinston [52] US. Cl. 34/122 [51] Int. Cl. F261) 11/02 [57] ABSTRACT [58] Field 61 Search 34/114 122 155 Hood for Commons Web dryer Supported crankarms for swinging movement toward and away from [56] References Cited web. Centering means provided to fix center of hood d cause expansion and contraction to occur from UNITED STATES PATENTS center to each end of hood. 3,167,408 1/1965 Justus et al. 34 122 3,183,607 5/1965 Beachler 34 122 3 Claims, 3 Drawlng Flgul'eS Pmmmnmzmm ROBERT C. PORTOUW INVENTOR BY BUCKHORN, BLORE, KLARQUIST & SPARKMAN ATTORNEYS R. 7 mm 4 2 B E D D E I N E l A D! 'SHEEIEQfZ ROBERT C. PORTOUW INVENTOR noon FOR DRYER BACKGROUND OF THE INVENTION carry away the moisture-laden air that results. In other processes wide webs are passed over flat or arcuate surfaces and beneath a hood to effect drying of ink or removal of moisture, either water or other liquid. It is necessary in installations of such types from time to time to adjust the position of the hood with respect to its spacing from the web being dried and also from time to time to get access between the web supporting memher and the hood for threading of the web or to effect repairs. Expensive and elaborate means have been devised heretofore to effect movement of the hood toward and away from the web. Numerous of these have been hampered in their operation due to the fact that the hood expands and contacts substantially as its temperature changes.

BRIEF DESCRIPTION OF THE INVENTION It is an objective of the invention to provide a new and improved arrangement for supporting a drying hood of the type described'above.

It is a principal object of the present invention to provide an inexpensive and effective arrangement for raising and lowering of the hood for a Yankee dryer which is unaffected by expansion and contraction of the hood structure.

In accordance with the present invention, a drying hood is supported adjacent the web to be dried on a crankarm-type of suspension upon which the hood swings toward and away from the web. The crankarms are suspended from a suitable frame and means are provided to center the hood with respect to the longitudinal center of the web and the frame so as to maintain the hood in a fixed position relative to its center so that all expansion takes place longitudinally of the hood to wards each of the opposite ends, thereby minimizing the amount of movement at either end. The centering means comprises a bowed rod connected at its center to the center point of the hood and journaled at its opposite ends in the supporting frame so that the hood swings on the centering rod as it swings on the crankarms in the raising or lowering operation.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a fragmentary end view of a dryer drum and hood embodying the invention;

FIG. 2 is a fragmentary elevation looking in the direction of the arrow 2-2 in FIG. 1; and

FIG. 3 is an enlarged fragmentary elevation looking in the direction of the arrow 3-3 in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION The invention is illustrated in connection with its application in a Yankee drum dryer of a papennaking machine. Such a dryer comprises a hollow drum or cylinder over the peripheral surface of which the paper web is carried as heat is applied to the web to remove moisture. In a typical papermaking machine a Yankee drum may have a diameter of 10 to 20 feet and a length of 15 to 25 feet. The drum 10 is suitably supported for rotation and since such systems are conventional and form no part of the present invention none is illustrated, nor is there illustrated in the present application the usual and conventional system for supplying heat (usually steam) to the interior of the drum 10 since such means forms no part of the present invention.

Mounted adjacent the periphery of the drum 10 is a pair of hoods 12, 14. The hoods 12, 14 are arranged to supply heated air to the exterior of the web carried on the drum 10 and to remove moisture-laden air which results from the evaporation of moisture from the web. Insofar as the invention is concerned any suitable arrangements can be provided for supplying air to and removing it from the hoods and any suitable arrangement can be provided for distributing the heated air over the surface of the web. Such means are, for example, shown in U.S. Pat. No. 2,928,185 and include inlet ducts 13 and removal ducts 15.

Frame means are provided for supporting the hoods 12, 14 adjacent the periphery of the cylinder 10. Inasmuch as the hoods 12, I4 and the supporting arrangements are mirror images of each other, details of the supporting arrangements will be described with particular reference only with respect to the hood 12, a substantially identical arrangement being provided with respect to the hood 14 as will become clear hereinafter.

The hood 12 is provided with a concavely curved surface 18 which is concentric with the cylinder 10 and extends over a substantial portion of the surface thereof beginning at the top center line of the cylinder down around one side surface thereof. The hood 12 extends the entire length of the cylinder 10, and it will be appreciated that because of this great length substantial expansion of the hood will take place over its length when it is heated from its cold condition to the elevated temperature at which drying occurs which is up to about l,000 F. in the drying of paper. Such expansion will amount to an inch or more and has presented serious problems in suitably supporting a hood so that it can be moved toward and away from the surface of the cylinder 10 to permit access thereto for threading of the web or cleaning or repair of the equipment. The apparatus of the invention is designed to overcome the problems presented by such expansion.

The supporting frame for the hoods 12, 14 comprises four corner posts 20, 22, 24, 26 situated in pairs at the ends of the cylinder 10. Between the posts 20, 22 extends a horizontal beam 28 and between the posts 24, 26 extends a beam 30. Extending longitudinally of the drum between the posts 22, 24 is a beam 32 and extending between the comer post 20, 26 is a beam 34. Extending upwardly from the beam 28 is a pair of uprights 36, 38 and similarly extending upwardly from the beam 30 is a pair of uprights 40, 42. The uprights 36, 40 are connected by a beam 44 and the uprights 38, 42 are connected by a beam 46.

Means are provided for supporting the hoods 12, 14 for a swinging movement toward and away from the surface of the drum 10. Suitably secured to the beam 28 is a pair of longitudinally spaced brackets 50, 52 in which crankarms 54, 56, respectively, are journaled for rotation about horizontal axes parallel to the axis of the drum 10. Self-aligning bearing means are preferably utilized to journal the crankarms 54, 56 in the brackets 50, 52 and which bearing means may be of any conventional known type. A sliding bearing arrangement of conventional type could also be used.

The opposite ends of the crankarms 54, 56 are journaled in the hood 12, again, preferably utilizing selfaligning bearings of any known suitable type. The crankarms 54, 56 form in effect a parallelogram supporting linkage. The crankarm 56 is formed with an offset portion to which is connected an elevating mechanism, including a chain 60 connected at its lower end to the crankarm 56 and at its upper end to the screw 62 of a screw jack driven from a shaft 64 suitably journaled on the beam 44 and adapted to be driven by a motor 66. Rotation of the shaft 64 effects elevation or lowering of the screw 62 which, in turn, will effect rotation of the crankarms 54, 56 to cause movement of the hood 12 toward and away from the drum or cylinder 10.

Means are provided to retain the hoods centered with respect to the cylinder 10, that is, means are provided to fix the position of the center of a hood relative to the lengthwise direction of the cylinder whereby expansion or retraction of the hood occurs in each direction from the center thereof and from the longitudinal center of the web carried thereon thereby minimizing the amount of movement of the ends of each hood. ln the illustrated embodiment of the invention such means comprises a centering rod 70 which is suitably journaled in a bracket 72 mounted on the hood 12. The centering rod may rotate relative to the bracket 72 but is restrained from longitudinal movement thereof relative to the bracket. The opposite ends of the centering rod 70 are suitably journaled in the frame means so that the rod may rotate relative to the frame but will not shift longitudinally with respect to the frame. As more clearly shown in FIG. 2 the centering rod 70 is bowed or V-shaped and the end portions are secured in brackets 74 mounted on the uprights 36, 40. The axes of rotation of the opposite ends of the rod 70 are coincident and parallel with one another and parallel to the axis of rotation of the cylinder 10. The axis of rotation of the ends of the rod are also offset from the axis of rotation of the rod through the bracket 72 by a distance which is equal to the throw of the crankarms 54, 56. Thus, as the hood 12 is raised or lowered the centering rod rotates within the brackets 72, 74 and does not interfere with the lifting or raising of the hood. At the same time, the centering rod maintains the hood centered with respect to the cylinder so that, as explained previously, the expansion of the hood takes place in opposite directions from the center thereof thereby minimizing the amount of movement at each end of the hood. The selfaligning bearings utilized with the crankarms 54, 56 are self-adjusting for the amount of misalignment which occurs as the hood expands or retracts, thus not interfering with the raising or lowering operation of the hood.

Having illustrated and described a preferred embodiment it will be apparent to those skilled in the art that the invention permits of modification in arrangement and detail.

l claim:

1. A dryer apparatus for removing moisture from material carried upon a rotating cylinder comprising:

a hood extending the length of said cylinder adjacent a portion of the periphery thereof;

frame means for supporting said hood;

means supporting said hood from said frame means for movement toward and away from said cylinder;

centering means connected to said frame means and to said hood at the longitudinal center thereof for restraining the center of said hood from movement longitudinally of said cylinder and permitting movement of said hood toward and away from said cylinder;

said centering means comprises a rod connected to each of said frame means and to said hood at the longitudinal center thereof and restraining the center of said hood from movement longitudinally of said cylinder; and

said rod means being pivotable with respect to said frame means and said hood about laterally spaced parallel axes.

2. A dryer apparatus as called for in claim 1 wherein said means supporting said hood comprises crankarms pivotally connected at one end to said frame means and at their opposite end to said hood and having a throw equal to the spacing between said axes.

3. A dryer apparatus for removing moisture from a material carried upon a rotating cylinder comprising:

a hood structure partially encircling the periphery of said cylinder and extending the length of said cylinder,

a supporting frame for said hood structure including a pair of frame members positioned one at each end of said cylinder,

parallelogram linkage means pivoting about axes parallel to the axes of said cylinder supporting said hood structure from said frame for movement toward and away from said cylinder periphery,

and centering means for retaining said hood structure centered with respect to said cylinder comprising a centering rod extending between said frame members and pivotally connected thereto for rotation about a second axis parallel to the axis of said cylinder,

means connecting said centering rod to said hood structure substantially at the center thereof and permitting rotation of said rod relative to said structure about a third axis parallel to said cylinder axis but restricting movement of said hood lengthwise of said rod,

said third axis being spaced from said second axis by a distance equal to the throw of said parallelogram linkage means. 

1. A dryer apparatus for removing moisture from material carried upon a rotating cylinder comprising: a hood extending the length of said cylinder adjacent a portion of the periphery thereof; frame means for supporting said hood; means supporting said hood from said frame means for movement toward and away from said cylinder; centering means connected to said frame means and to said hood at the longitudinal center thereof for restraining the center of said hood from movement longitudinally of said cylinder and permitting movement of said hood toward and away from said cylinder; said centering means comprises a rod connected to each of said frame means and to said hood at the longitudinal center thereof and restraining the center of said hood from movement longitudinally of said cylinder; and said rod means being pivotable with respect to said frame means and said hood about laterally spaced parallel axes.
 2. A dryer apparatus as called for in claim 1 wherein said means supporting said hood comprises crankarms pivotally connected at one end to said frame means and at their opposite end to said hood and having a throw equal to the spacing between said axes.
 3. A dryer apparatus for removing moisture from a material carried upon a rotating cylinder comprising: a hood sTructure partially encircling the periphery of said cylinder and extending the length of said cylinder, a supporting frame for said hood structure including a pair of frame members positioned one at each end of said cylinder, parallelogram linkage means pivoting about axes parallel to the axes of said cylinder supporting said hood structure from said frame for movement toward and away from said cylinder periphery, and centering means for retaining said hood structure centered with respect to said cylinder comprising a centering rod extending between said frame members and pivotally connected thereto for rotation about a second axis parallel to the axis of said cylinder, means connecting said centering rod to said hood structure substantially at the center thereof and permitting rotation of said rod relative to said structure about a third axis parallel to said cylinder axis but restricting movement of said hood lengthwise of said rod, said third axis being spaced from said second axis by a distance equal to the throw of said parallelogram linkage means. 